(a) Field of the Invention
The present invention relates to a camera accessory such as an exchangeable lens or an electronic flash device and, more particularly, to such an accessory selectively attached to a camera and provided with an encoder which generates data representative of the setting position of a driven member of the camera accessory, such as a focusing ring, a focal length adjusting ring and a diaphragm aperture setting ring of the exchangeable lens, and an emitted light angle adjusting mechanism of the electronic flash device.
(b) Description of the Prior Art
Exchangeable lenses are known which are provided with an encoder and a ROM (read only memory) which stores lens data such as the camera-to-object distance to be focused on by the lens (hereinafter referred to as a focused distance), a focal length, and a diaphragm aperture value, etc. that are determined on the basis of the setting position of the above-mentioned driven member. The ROM is accessed by the data of the encoder so that a variety of data relating to the exchangeable lens are sent to the camera from the ROM.
In such an exchangeable lens, the positional relationship between the relative positions of the relatively movable members of the encoder and the set position of the driven member (for example, the focal length adjusting ring), that is, the relative position between an encoder pattern fixed on a lens barrel of the exchangeable lens and a brush linked with the driven section must be accurately adjusted at the time of assembly to produce correct data from the encoder. In this case, if such adjustment is performed with human eyes, high accuracy of the adjustment of the relative position between the encoder pattern and the brush cannot be achieved mainly because the encoder pattern is small in size. Alternatively, if a particular encoder pattern for adjustment is employed to produce an electrical signal, the whole encoder becomes bulky because of the additional provision of the particular pattern. Besides, a jig for the adjustment must be coupled with the lens barrel in the process of assembly, and the jig and its related wires must be removed after the adjustment. The adjusting operation consequently is complicated and time-consuming.